Wireless measurement.

H

Helge A. Bentsen

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Jan 19, 2011
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Oslo, Norway, Norway
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I'm tired of running cables across seats and floors when doing system alignments out on tour, so I seriously consider going wireless.

Apart from the Lectrosonics TM400, is there anything else that is usable for this kind of work?
I have a spare Sennheiser 5000 bodypack/3000 reciever available, would it be possibe to obtain usable and consistent measurements using this?
 
Re: Wireless measurement.

I know someone (on this forum?) has successfully used one of the 2.4gHz digital mic systems... I believe the Sabine. Takes a little hacking to cable it up, but it is maybe half the price of the Lectrosonics. Of course, the Lectro is the only one I have used, and probably the only one I will ever use. It is fantastic, and built like a brick shithouse. Also operates in the relatively uncrowded 900mHz band. How relevant that is from a guy who now sells component loudspeakers for a living, I don't know! 8O~8-O~:shock:

P.S. Multi-channel measurement and at least one wireless measurement mic, combined with my Leica laser measure, are the greatest time saving and accuracy increasing tools I have ever owned. Even just an additional mic at FOH while another mic floats significantly increases my measurement confidence.
 
Re: Wireless measurement.

I've also been wondering about some of the budget digital systems showing up from Shure that I'm told have no companding.. would a PGXD be any good? is there any way to test it?
like, does a loopback test through a wireless link tell us all we need to know, or are there other things going on that are hard to measure but that can screw with measurements (is that even possible?)

Jason
 
Re: Wireless measurement.

Helge Dr. Bentsen said:
I'm tired of running cables across seats and floors when doing system alignments out on tour, so I seriously consider going wireless.

Apart from the Lectrosonics TM400, is there anything else that is usable for this kind of work?
I have a spare Sennheiser 5000 bodypack/3000 reciever available, would it be possibe to obtain usable and consistent measurements using this?
Click to expand...
The problem with using a regular wireless mic setup (forget the actual quality of the mic element here) is the companding circuit that is used. Compression and expansion. The Lectrosonics does not have any companding-so therefore it is a linear system.

Sure you can use a regular wireless-but the results will not be accurate. So it depends on what you are trying to actually do.

You ALWAYS HAVE to question the result of what any meter "shows" you.

I am in the process of doing some eval for a new type of product that I am very interested in using-and it is causing me to have to rethink and custom build some test setups in order to attempt to get good/meaningful measurements.

Just because it "shows up on the screen" does NOT mean that it is correct. You have to look at everything in the chain to see if something is "screwing" with you. Maybe even in an intended-but unexpected way.
 
Re: Wireless measurement.

Ivan Beaver said:
The problem with using a regular wireless mic setup (forget the actual quality of the mic element here) is the companding circuit that is used. Compression and expansion. The Lectrosonics does not have any companding-so therefore it is a linear system.
Click to expand...

From what I was told by a good friend that works at develkopement with Shure the new ULX-D has no companding circuit. I specifically asked him about it in reference to using it as a wireless test rig.
 
Re: Wireless measurement.

It is possible to bypass the companding in the old Sennheiser systems, i know that the Danish radio used to do it. They traded the increase in noise for the lack of companding artifacts.
It would possible be easier to buy one of the digital systems.
 
Re: Wireless measurement.

Jens Bacher said:
It is possible to bypass the companding in the old Sennheiser systems, i know that the Danish radio used to do it. They traded the increase in noise for the lack of companding artifacts.
It would possible be easier to buy one of the digital systems.
Click to expand...
Jens are they selling them, now that they have to buy new systems??
 
Re: Wireless measurement.

Brad Galvin said:
From what I was told by a good friend that works at develkopement with Shure the new ULX-D has no companding circuit. I specifically asked him about it in reference to using it as a wireless test rig.
Click to expand...

What I would do (before I trusted it) would be to measure a loudspeaker with a corded mic and then with the wireless mic and see what the differences are.

Or better yet, run each mic into the dual FFT measurement system and look at what the differences are. It should be a flat line on both phase and magnitude. If it is not, you have to determine if the areas of difference are important or not to you and what you are trying to measure. In some cases it may be a big deal-other cases not so much.
 
Re: Wireless measurement.

so I had a PGXD on the shelf that I bought for evaluation but have been too busy to even open up.
here is what I got from a loopback test using a PGXD1 beltpack.
Red trace is a hardwired loopback, green trace is the PGXD.
obviously it's not going to be very helpful for phase measurements, but could be fine for basic amplitude readings.

of course then the next issue is how to get phantom powered mics working on a beltpack with only bias power :(

Jason
 

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Re: Wireless measurement.

Jason Lavoie said:
so I had a PGXD on the shelf that I bought for evaluation but have been too busy to even open up.
here is what I got from a loopback test using a PGXD1 beltpack.
Red trace is a hardwired loopback, green trace is the PGXD.
obviously it's not going to be very helpful for phase measurements, but could be fine for basic amplitude readings.

of course then the next issue is how to get phantom powered mics working on a beltpack with only bias power :(

Jason
Click to expand...
You might want to try with different drive levels.
 
Re: Wireless measurement.

There are a two major advantages with the Lectrosonics system. The first as has already been discussed is accurate response with no companding. The second is that the HM transmitter plugs right on to the back of your measurement mic and provides a true +48 volts. With any other option, you're going to have to get an external phantom supply and put that in line between your mic and whatever wireless beltpack you use. The Lectrosonics also samples at a higher rate compared to other offerings (88.2KHz).
 
Re: Wireless measurement.

Ivan Beaver said:
You might want to try with different drive levels.
Click to expand...

I did try adjusting the drive level (both from the source and from the gain adjustment on the beltpack) and there was no noticeable change in the shape of the gain or phase plot. I'm not currently setup in a way that would make it easy for me to measure for any compression like Langston did, but maybe if I can find some time.

Jason
 
Re: Wireless measurement.

After some extensive googling around and reading I've come to the conclusion that if I go wireless, I go with the Lectrosonics TM400. There are other options, but it has the best reviews and it fits in our wireless regulations.

Now all I have to do is find a good deal on it, i'd make me verry happy if anybody could point me in the right direction :)
 
Re: Wireless measurement.

I've been using a plain Shure UR2 handheld for balconys and other places where a cable is to much effort. Yes, it sucks in the frequencyresponse but as long as it sucks everywhere in the venue the system is consistent. With the receiver set at linelevel and split to both smaart and the processor I can also use the mic to talk trough the PA.
You have to accept there is not very much above 10k, but on the plus side I can tune the PA without a working FOH console with equipment that almost every client brought along anyway.
 
i just tested with new sennheiser xsw-d... they claim them self as the xsw-d are digital wireless... the phase & the response doesn't look like they are digital... i'm just curious...
 

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Digital in and of itself does not mean free from phase change though.
They could perfectly well be using digital equivalents of conventional HPF and LPFs to limit bandwidth, producing a curve like that.
 
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